Battery Modules and Energy Storage Devices

Abstract

An embodiment of the present invention relates to a battery module and an energy storage device, and provides an energy storage device including a battery rack including a plurality of battery modules and a rack fuse that cuts off a circuit when an overcurrent occurs in the battery rack, wherein each of the plurality of battery modules includes a battery cell and a module fuse that cuts off the circuit when an overcurrent occurs in the battery module, and the module fuse has a voltage specification that can accommodate the output voltage of the battery rack and a short-circuit specification that is lower than the short-circuit specification of the rack fuse.

Description

[Technical field]

[0001] The present invention claims the benefit of priority based on Korean Patent Application No. 10-2020-0044257, filed on April 10, 2020, and all contents disclosed in the documents of the Korean patent application are incorporated by reference into this specification.

[0002] An embodiment of the present invention relates to a battery module and an energy storage device, and more particularly to a battery module and an energy storage device provided with a fuse for cutting off an overcurrent. [Background technology]

[0003] In recent years, with the spread of electronic devices such as smartphones and electric vehicles, and the expansion of infrastructure for energy storage systems (ESS), active research has been conducted on secondary batteries as a power supply source.

[0004] In the case of an energy storage device, not only is it necessary to store a large amount of electrical energy, but it is also required to have a high output. Therefore, in the energy storage device, the secondary battery is provided in the form of a battery rack consisting of a plurality of battery modules and a rack controller that manages the plurality of battery modules. Each of the plurality of battery modules again includes a battery pack in which a plurality of battery cells are connected in series and / or parallel, and a module controller that manages the operation of the battery pack.

[0005] In an energy storage device, if a short circuit occurs, it can lead to a major accident such as a fire, so for safety reasons, various configurations are provided to cut off such a short circuit. Currently, a fuse is connected as a passive element in a battery system such as an energy storage device. When a short circuit occurs, the fuse cuts off an overcurrent for a short moment to prepare for a short circuit accident.

[0006] The fuses in such battery racks are not designed to handle short circuits at the module level. Therefore, the battery system is also provided with a module fuse to meet the UN Transportation Testing (UN / DOT38.3) standard. UN / DOT38.3 is a test regulation to ensure safety during transportation of lithium-ion batteries. UN / DOT38.3 includes provisions requiring protection against short circuits of modules when batteries are transported in a modular state, and a module fuse is provided to meet this requirement. A module fuse having a voltage specification that meets the module voltage is selected so that there are no problems in a short circuit test of the installed battery module.

[0007] However, if a short circuit occurs in the battery rack after the battery modules are finally installed in the battery rack, the module fuse may operate and blow before the rack fuse does, and the system voltage, i.e., the output voltage of the battery rack, may be applied to the module fuse. In this case, the module fuse may be unable to withstand the system voltage and may break, causing damage to other components. Summary of the Invention [Problem to be solved by the invention]

[0008] The embodiments of the present invention have been made to solve the above problems, and aim to provide a battery module and energy storage device that are safe, cost competitive, and prevent a decrease in energy density. [Means for solving the problem]

[0009] In order to solve the above-mentioned technical problems, according to one aspect of an embodiment of the present invention, an energy storage device is provided, comprising: a battery rack including a plurality of battery modules; and a rack fuse that cuts off a circuit when an overcurrent occurs in the battery rack, wherein each of the plurality of battery modules includes a battery cell and a module fuse that cuts off the circuit when an overcurrent occurs in the battery module, and the module fuse has a voltage specification that is compatible with the output voltage of the battery rack and a short-circuit specification that is lower than the short-circuit specification of the rack fuse.

[0010] According to another feature of this embodiment, the module fuse can be blown slower than the rack fuse when a short circuit occurs in the battery rack. According to another feature of the present embodiment, the module fuses are such that when a short circuit occurs in the battery rack, only the rack fuse is blown.

[0011] According to yet another feature of the present embodiment, the module fuse may begin to blow later than the rack fuse has completed blowing when a short circuit occurs in the battery rack.

[0012] According to yet another feature of this embodiment, if a short occurs in the battery rack causing the rack fuse to blow, the module fuse may not operate. According to yet another feature of the present embodiment, when a short circuit occurs in the battery module, the module fuse can be cut off.

[0013] In order to solve the above-mentioned technical problems, according to another aspect of an embodiment of the present invention, there is provided a battery module in an energy storage device, which is used to include a plurality of battery modules in a battery rack and includes a rack fuse that cuts off a circuit when an overcurrent occurs, the battery module comprising a plurality of battery cells and a module fuse that cuts off the circuit when an overcurrent occurs, the module fuse having a voltage specification compatible with the output voltage of the battery rack and a short-circuit specification that is lower than the short-circuit specification of the rack fuse.

[0014] According to another feature of this embodiment, when a short circuit occurs in the battery rack, the module fuse can start to blow later than the rack fuse has completely blown.

[0015] According to another feature of the present embodiment, when a short circuit occurs in the battery module, the module fuse can be cut off. Effect of the Invention

[0016] With the above-described configuration, it is possible to provide a battery module and an energy storage device that are safe, yet capable of preventing a decrease in price competitiveness and energy density. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram showing a configuration of an energy storage device according to an embodiment of the present invention; [Diagram 2] 1 is a diagram showing a configuration of a battery module according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a schematic circuit diagram of an energy storage device according to an embodiment of the present invention. [Figure 4] 4 is a diagram showing an example in which a short circuit occurs in the energy storage device according to FIG. 3. [Diagram 5] 4 is a diagram showing another example in which a short circuit occurs in the energy storage device shown in FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this document, the same reference numerals are used to refer to the same components in the drawings, and duplicated descriptions of the same components will be omitted.

[0019] For the various embodiments of the present invention disclosed in this document, specific structural or functional descriptions are merely exemplified for purposes of describing the embodiments of the present invention, and the various embodiments of the present invention may be embodied in various forms and should not be construed as being limited to the embodiments described in this document.

[0020] The terms "first," "second," "first," or "second" used in the various embodiments may modify various components regardless of order and / or importance and do not limit the components. For example, a first component may be named as a second component, and similarly, a second component may be renamed as a first component without departing from the scope of the invention.

[0021] The terms used in this document are merely used to describe a particular embodiment and are not intended to limit the scope of other embodiments. A singular expression may include a plural expression unless otherwise clearly indicated in the context.

[0022] FIG. 1 is a diagram showing a configuration of an energy storage device according to one embodiment of the present invention. Referring to FIG. 1, an energy storage device 1 is a unit for storing energy in an energy storage system. An energy storage system may be configured to include a plurality of energy storage devices 1. The energy storage device 1 is provided in the form of a battery rack. The battery rack has a chassis on which a plurality of battery modules 10 and a rack controller for controlling the entire battery rack are mounted. In the following description, the terms energy storage device and battery rack may be used interchangeably.

[0023] The energy storage device 1 can be configured to include a battery module made of a chargeable and dischargeable secondary battery. The energy storage device 1 can supply stored power to a load or to a power grid. The energy storage device 1 can also be charged by receiving power from the power grid.

[0024] As shown in FIG. 1, the energy storage device 1 may include a plurality of battery modules 10-1 to 10-N, a rack controller (RBMS, Rack Battery Management System), a rack protection unit (RBPU, Rack Battery Protection Unit), and the like.

[0025] The multiple battery modules 10-1 to 10-N are unit components that can be attached to the energy storage device 1, and each is configured to be able to charge and discharge power (hereinafter, when there is no need to distinguish between the multiple battery modules and describe them separately, the drawing reference numerals will be written as "battery modules 10"). The battery module 10 is configured so that it can be transported by itself before being assembled into a battery rack as the energy storage device 1. The multiple battery modules 10 can be connected to each other in series and / or parallel within the energy storage device 1 according to the required specifications of the energy storage device 1. That is, the multiple battery modules 10 can provide a required output according to the configuration of the series and / or parallel connection.

[0026] Each battery module 10 may include a battery pack 11, a module controller 12, a switching unit 13, and a module protection unit 14 (Module BPU), etc. Figure 2 is a diagram showing the configuration of a battery module according to one embodiment of the present invention.

[0027] 2, the battery pack 11 may include one or more battery cells C, which are unit components for storing power. Depending on the required specifications of the battery pack 11, a plurality of battery cells may be connected to each other in series and / or parallel. That is, the number and connection form of the battery cells C may be determined according to the required output (voltage, current, etc.) of the battery module 10. The battery cells C may be lithium-ion (Li-ion) batteries, lithium-ion polymer (Li-ion polymer) batteries, nickel-cadmium (Ni-Cd) batteries, nickel-metal hydride (Ni-MH) batteries, etc., and are not limited thereto as long as they are rechargeable batteries.

[0028] The module controller 12 (or also referred to as the "module BMS") controls and manages the overall operation of the battery module 10. The module controller 12 can detect the temperature of the battery module 10, the voltage and current output from the battery module 10, etc. The battery module 10 can calculate parameters such as SOC, which indicates the state of charge, and SOH, which indicates the degree of deterioration, from the values ​​of temperature, voltage, current, etc. detected by directly measuring or receiving them from the outside. The module controller 12 can include measuring means such as sensors at appropriate positions in the battery module 10 or the energy storage device 1 to detect the voltage, current, temperature, etc.

[0029] The module controller 12 can transmit values ​​of temperature, voltage, current, etc., and calculated values ​​of SOC, SOH, etc. to an external device. The external device may be a higher-level controller, and in this embodiment, can transmit values ​​of detected temperature, voltage, current, etc., and calculated values ​​of SOC, SOH, etc. to a rack controller 20 that manages the energy storage device 1.

[0030] The module controller 12 may include a variety of components, such as a microcomputer as a controller that executes computer programs and controls the overall operation of the module controller 12 in order to control and manage the overall operation of the battery module 10, a memory that stores computer programs necessary for the operation of the module controller 12, input / output devices such as sensors and measuring means, a communication device for communicating with external devices, and other peripheral circuits.

[0031] The switching unit 13 may be a device that supplies power to a grid or a load, or receives power from the grid, when the battery module 10 is charged or discharged. The switching unit 13 may be a relay, a contactor, or the like. The operation of the switching unit 13 may be controlled by the module controller 12.

[0032] The module protection unit 14 may include a configuration for stable operation of the battery module 10. The module protection unit 14 may include a cooling means such as a cooling fan for controlling the temperature inside the battery module 10. The module protection unit 14 may also include a module fuse MF for cutting off a current path when an overcurrent occurs due to a short circuit or other reasons. That is, the battery module 10 may be provided with a module fuse MF that cuts off a circuit when an overcurrent occurs.

[0033] When an overcurrent flows through the battery module 10, the module fuse MF melts due to heat generated by electrical energy. When the module fuse MF melts to cut off the flow of current, a certain voltage is applied during that time. After melting, the module fuse MF must withstand the certain voltage applied across both ends. The specific specifications and features of the module fuse MF will be described later.

[0034] The rack controller 20 can control relays to charge the battery rack or discharge the battery rack to a system or a load. The rack controller 20 can monitor various parameters (e.g., voltage, current, temperature, etc.) in the battery rack and control each protection means in the rack protection unit 30 based on the results.

[0035] The rack controller 20 can communicate with the module controllers 12 included in each of the multiple battery modules 10 included in the battery rack. The rack controller 20 can receive data on the status of the battery packs 11 from the module controllers 12 and control the protection means in the rack protection unit 30 based on the data. The rack controller 20 can also transmit control signals to the module controllers 12 for controlling the operation of the battery modules 10 based on the data from the module controllers 12. The rack controller 20 can communicate with the multiple module controllers 12 via wired and / or wireless communication.

[0036] The rack protection unit 30 may include a configuration for stable operation of the battery rack, similar to the module protection unit 14. The rack protection unit 30 may include a cooling means such as a cooling fan for controlling the temperature inside the battery rack. The rack protection unit 30 may also include a rack fuse RF for cutting off a current path when an overcurrent occurs due to a short circuit or other reasons. That is, the energy storage device 1 may include a rack fuse RF for cutting off a circuit when an overcurrent occurs in the battery rack. Specific specifications and features of the rack fuse RF will be described later.

[0037] In the energy storage device 1 configured as above, at least some of the battery modules 10 and the rack fuse RF are connected in series to each other. Figure 3 is a schematic circuit diagram of the energy storage device 1 according to one embodiment of the present invention.

[0038] 3, at least some of the battery modules 10, 10-1 to 10-N, are connected in series to one another, and a rack fuse RF is connected in series to the battery modules 10-1 to 10-N connected in series. RACK(+) and RACK(-) indicate output terminals of the battery rack. For ease of explanation, FIG. 3 shows only one battery cell as the battery pack 11, and only the battery pack 11 and the module fuse MF are shown.

[0039] In the energy storage device 1 configured as in FIG. 3, a case may be assumed in which a short circuit occurs in the battery rack or in the battery module 10.

[0040] Conventionally, in order to satisfy the UN / DOT3.83 regulations, a fuse having a specification capable of withstanding the output voltage of a battery module has been used as a module fuse. For example, in the case of a battery module that outputs a voltage of about 50 to 100 VDC, a fuse capable of withstanding a voltage of about 120 to 150 VDC has been used. However, commercial products are used as such module fuses, and the fuses used have a short-circuit specification capable of passing a current of about 20 kA.

[0041] However, while conventional module fuses could protect battery modules against module short circuits that occur when the battery modules are used or transported individually, they had the problem of not being able to protect battery modules against module short circuits that occur when multiple battery modules are mounted on a battery rack.

[0042] Therefore, a solution was needed to protect the battery modules not only when they are used individually but also when they are attached to a battery rack. Also, the higher the specifications of the fuse, the higher the volume and price. Therefore, it is necessary to consider how to avoid a decrease in energy density due to volume without lowering the price competitiveness of the battery module.

[0043] The module fuse MF according to this embodiment is a fuse having specifications compatible with the voltage (output voltage of the battery rack) output by the energy storage device 1. The module fuse MF can have the same voltage specifications as the rack fuse RF.

[0044] If a short circuit occurs when multiple battery modules 10 are attached to a battery rack, the voltage applied to the module fuse MF may vary. In this case, if a short circuit occurs in the battery rack and the uppermost module fuse MF melts first, a voltage close to the system voltage may be applied across the module fuse MF (see FIG. 5). For example, a voltage of about 1,000 to 1,500 VDC may be applied across the module fuse MF. Therefore, the module fuse MF is selected to have a voltage specification that can withstand the system voltage, rather than a conventional voltage specification that can withstand the 50 to 100 VDC output voltage of the battery module.

[0045] On the other hand, the module fuse MF according to the present embodiment has a lower short-circuit specification than the rack fuse RF. As described above, the higher the specification of the fuse, the larger the volume and the price. Therefore, the module fuse MF has a lower short-circuit specification than the short-circuit specification applied to the rack fuse RF provided in the energy storage device 1.

[0046] In a fuse, there is a trade-off between voltage specification and short-circuit specification. In other words, as a modular fuse MF, a higher voltage specification than conventional ones can be selected in exchange for lowering the short-circuit specification, thereby suppressing increases in price and volume.

[0047] As a further embodiment, the module fuse MF can be configured to break slower than the rack fuse RF when a short circuit occurs in the battery rack. The breaking speed of the module fuse MF and the rack fuse RF can be adjusted by appropriately selecting the components, thickness, length, etc. of the melting portion of the fuse. In other words, by making the rack fuse RF break before the module fuse MF when a short circuit occurs in the battery rack, the battery module 10 can be safely protected even if the short circuit specification of the module fuse MF is lowered.

[0048] Preferably, the module fuse MF can be configured so that only the rack fuse RF is cut off when a short circuit occurs in the battery rack. More preferably, the module fuse MF can be configured so that when a short circuit occurs in the battery rack, the module fuse MF starts to melt later than the rack fuse RF has completely melted. Even more preferably, when a short circuit occurs in the battery rack and the rack fuse RF is cut off, the module fuse MF can be configured so that it does not operate at all.

[0049] In other words, if a short circuit occurs in the battery rack, the module fuse MF will not operate at all and only the rack fuse RF will operate, thereby preventing a situation in which the module fuse MF must be replaced unnecessarily.

[0050] Fig. 4 is a diagram showing an example in which a short circuit occurs in the energy storage device 1 according to Fig. 3. In this example, as described above, a short circuit occurs in the battery rack.

[0051] As shown in Figure 4, if the node between rack fuse RF and the output terminal RACK(+) is short-circuited to ground, rack fuse RF melts and cuts off the current path. Then, a voltage V1 corresponding to the system voltage is applied across rack fuse RF. Since rack fuse RF has a voltage specification that can withstand the system voltage, no additional damage occurs even after the circuit is cut off.

[0052] When a short circuit occurs in the battery rack, the module fuse MF does not operate. Since the rack fuse RF is cut off and no current flows, the module fuse MF is not loaded, and the battery module 10 is also maintained in a safe state.

[0053] Next, a case where a short circuit occurs in the battery module 10 rather than in the battery rack will be described. When a short circuit occurs in the battery module 10, the module fuse MF melts and cuts off the circuit. In this case, the rack fuse RF does not operate. When the module fuse MF melts due to a short circuit in the battery module 10, the voltage applied to the module fuse MF may vary. In the example of FIG. 3, when a short circuit occurs near the bottommost battery module 10-N, the output voltage of the battery module 10 is applied across the module fuse MF. In contrast, in the example of FIG. 3, when a short circuit occurs near the topmost battery module 10-1, the system voltage is applied across the module fuse MF.

[0054] Fig. 5 is a diagram showing another example in which a short circuit occurs in the energy storage device 1 shown in Fig. 3. In this example, as described above, a short circuit occurs in the uppermost battery module 10-1 among the battery modules 10.

[0055] As shown in FIG. 5, when a node between the battery module 10-1 and the rack fuse RF is short-circuited to ground, the module fuse MF melts and cuts off the current path. A voltage V2 close to the system voltage is applied across the module fuse MF. However, since the module fuse MF according to the embodiment of the present invention has a voltage specification that can withstand the system voltage, no additional damage occurs even after the circuit is cut off. Therefore, the battery module 10 is maintained in a safe state.

[0056] As described above, the module fuse MF provided in the battery module 10 has the same voltage specification as the rack fuse RF, and has a lower short-circuit specification than the short-circuit specification of the rack fuse RF. This configuration makes it possible to safely handle not only cases in which the battery modules 10 operate individually, but also cases in which a module short circuit occurs in the battery modules 10 in a battery rack state.

[0057] The terms "comprise", "constitute", or "have" described above, unless otherwise specified to the contrary, mean that the relevant element can be contained, and should not be interpreted as excluding other elements, but as including other elements. All terms, including technical or scientific terms, may be diluted to have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs, unless otherwise defined. Commonly used terms, such as terms defined in a dictionary, should be interpreted as consistent with the contextual meaning of the relevant art, and should not be interpreted in an ideal or overly formal sense unless clearly defined in the present invention.

[0058] The above description is merely illustrative of the technical idea of ​​the present invention, and a person having ordinary knowledge in the technical field to which the present invention belongs may make various modifications and variations within the scope of the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are for the purpose of explanation and not for the purpose of limiting the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments. The scope of protection of the present invention should be interpreted according to the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

[0059] 1 Energy storage device 10 Battery module 10-1~10-N Battery Module 11 Battery pack 12 Module Controller 13 Switching section 14 Module Protection Unit 20 Rack Controller 30 Rack Protection Unit

Claims

1. A battery rack including a plurality of battery modules connected in series; a rack fuse connected in series with the plurality of battery modules and configured to cut off a circuit when an overcurrent occurs in the battery rack; Including, each of the plurality of battery modules includes a battery cell and a module fuse that cuts off a circuit when an overcurrent occurs in the battery module; An energy storage device, characterized in that at least the uppermost module fuse among the module fuses, which is closest to the positive output terminal of the battery rack, has a voltage specification compatible with the output voltage of the battery rack and is blown with a smaller current than the rack fuse.

2. The energy storage device of claim 1 , wherein the uppermost module fuse is cut off later than the rack fuse when a short circuit occurs in the battery rack.

3. The energy storage device according to claim 2 , wherein the uppermost module fuse is such that only the rack fuse is cut off when a short circuit occurs in the battery rack.

4. The energy storage device of claim 3 , wherein the uppermost module fuse starts to blow later than the rack fuse completes blowing when a short circuit occurs in the battery rack.

5. The energy storage device of claim 3 , wherein when a short circuit occurs in the battery rack and the rack fuse is blown, the uppermost module fuse does not operate.

6. 2. The energy storage device of claim 1, wherein the topmost module fuse is cut off when a short circuit occurs in the battery module.

7. A battery module among a plurality of battery modules connected in series for use in a battery rack in an energy storage device, comprising: The energy storage device includes a rack fuse that cuts off a circuit when an overcurrent occurs in the battery rack, and the plurality of battery modules are connected in series with the rack fuse; Each of the plurality of battery modules is A plurality of battery cells; A module fuse that cuts off the circuit when an overcurrent occurs; Equipped with a battery module, wherein at least an uppermost module fuse among the module fuses, which is closest to the positive output terminal of the battery rack, has a voltage specification compatible with the output voltage of the battery rack and is blown by a smaller current than the rack fuse.

8. 8. The battery module according to claim 7, wherein the uppermost module fuse starts to blow later than the rack fuse is completely blown when a short circuit occurs in the battery rack.

9. 8. The battery module according to claim 7, wherein the uppermost module fuse is cut off when a short circuit occurs in the battery module.

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